Syrian rebels could be armed by the UK in a fresh push to oust President Bashar Assad and end the bloodshed after David Cameron ordered officials to re-examine all options.

A Downing Street official said the Prime Minister wanted to put previously rejected measures “back on the table” amid frustration at the failure to halt the 20-month conflict.

Mr Cameron had vowed to redouble his efforts after visiting a refugee camp in Jordan and hearing “horrendous” stories of some of those who have fled the violence.

British diplomats are already set for talks with opposition military commanders as part of the renewed drive – which the premier said should be a top priority for newly-re-elected US president Barack Obama.